Dynamic measurement on nonlinear parameters of magnetic circuit of a balanced armature transducer

The balanced armature transducer is driven by the force between magnetic materials. However, the bending motion of the magnetized armatures interferes with the magnetic characteristics, resulting in inherent nonlinear characteristics in the magnetic circuit. To obtain the four nonlinear parameters that represent the nonlinear magnetic properties of a balanced armature transducer, the relationships between the coil impedance, vibration displacement and these four nonlinear parameters are derived using Kirchhoff’s law and the forced vibration equation. Based on these relations, a method for measuring the nonlinear parameters of the magnetic circuit using dynamic measurement technology is proposed. An experimental apparatus for a balanced armature transducer has been developed and the nonlinear parameters obtained by dynamic measurement are consistent with the simulation results. The results also show that, while increasing the magnetic strength in the magnetic circuit of a balanced armature transducer improves the driving force, it also brings the reluctances of the armature closer to saturation, leading to more significant nonlinear characteristics.